Hydroponics

Hydroponics is a method of gardening
without
soil. By eliminating the soil, one also eliminates a large number of
soil borne
pests & diseases. Inputs can be optimized to achieve greater control
over
the plants.

A simple hydroponic system requires a
container
to hold the aggregate and nutrient solution. The aggregate is an inert
medium
for providing a support structure for the roots. Some examples of
materials
which can be used as aggregates are sand, gravel, rockwool, perlite,
vermiculite and shards of brick. I have even used a block of sponge to
serve as
an aggregate to make an interesting display!

Use of aggregate is not essential and can
be
eliminated if a method of supporting the plant can be worked out. I have
used a
clay vessel with a narrow neck. Plant support was achieved by wrapping a
sponge
around the stem of the plant and inserting it into the vessel so that
the
sponge is firmly wedged in the neck and the roots freely dangle in the
nutrient
solution. As the plant grew, external supports were used to support the
folliage.

Nutrient solution can be prepared from a
ready-made dry mix formulation by mixing 1 level teaspoon in 3.8 liters
of
water. This will give a pH in the range of 6 to 6.5
.

A simple formulation for a dry mix nutrient
is
shown in the table below:

Fertilizer Salts

Quantity in Grams

Nutrients Supplied

Sodium Nitrate

350

Nitrogen

Potassium sulphate

110

Potassium, sulphur

Superphosphate

140

Phosphorus, calcium

Magnesium sulphate

100

Magnesium, sulphur

Iron sulphate

A pinch

Iron

There are two methods of applying the
nutrients,
active and passive. In the active method, the nutrient is pumped onto
the
aggregate and allowed to drain off. This method is difficult
to implement
without automation. In the passive method, the nutrients are allowed to
be
wicked up from a reservoir into the aggregate. In my passive method
(using a
clay vessel with a narrow neck) the aggregate was eliminated and the
nutrient
solution was directly filled into the vessel. Although literature
cautions against
water-logging, the variety of plants I have grown did not appear to
suffer from
this problem since plants grown hydroponically quickly adapt to the
situation
by growing special roots which trap air within them.

The nutrient solution must be periodically
replaced since replacing only the nutrients consumed is not a viable
proposition unless one has the expensive setup to carryout chemical
analysis. I
have replaced the nutrient solution every alternate day and used the
spent
solution to water other plants which were being grown conventionally in
the
soil. Every day the nutrient solution was topped up in the container
with water to
compensate for evaporation and to keep the pH within the acceptable
range.

I have grown tomatoes, cucumbers and
capsicums by
the method outlined above. Tomatoes are perhaps the easiest to grow. I
was
delighted with the vigorous growth of my plants which grew as vines to a
height
of 6 feet. The plants were grown in the open but I provided a screen
above to
diffuse the strong sunlight in summer to prevent scorching the leaves.

I came to know about Hydroponics after
reading a
wonderful book by Richard E. Nicholls entitled "Begining
Hydroponics"
which is a beginner's guide to growing vegetables, house plants, flowers
and
herbs without soil. The book is published by Running Press,
Philadelphia,
Pennsylvania.